Description: 1. Provide cell culture expertise to investigators with the Program Project. 2. Maintain a supply of normal fibroblasts and keratinocytes from multiple sources, stored frozen in liquid nitrogen, for used by Core B and the other projects. 3. Genetically modify skin cells using retroviral vectors provided by Core C. 4. Clone and/or expand the genetically modified cells for used in experiments in Projects I, III, IV and V. 5. Maintain a supply of genetically modified cells (normal and immortalized), stored in liquid nitrogen for recovery and expansion when needed. 6. Culture dermal papillae cells for Project 4. 7. When volume needs for plasmid DNA for use in Project IV exceeds the capability of Core C to supply same, Core B will prepare and purify the required amounts of plasmid DNA. 8. Test genetically modified cells for transgene expression (protein product and message) in vitro for Projects I, IV and V. 9. Graft genetically modified cells of the skin in the appropriate constructs onto athymic mice for Project III. 10. Prepare and maintain de-epidermized dermic (also called acellular) for Projects I and V. 11. Transplant the tetracycline responsive immortalized genetically modified keratinocytes of Project V to nude mice. 12. Maintain a catalog of the stored cells.